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A systematic analysis of the XPS Fe 2p 3/2 core-level photoelectron lines and their satellite structures gave insight into the electronic properties of a series of ferrocenyl-containing chalcones with the structure Fc CO CH CH C 6 H 4 R, where R is in the para -position on the phenyl ring and R OCH 3 ( 1 ), CH 3 ( 2 ), C 6 H 5 ( 3 ), t Bu ( 4 ), H ( 5 ), Br ( 6 ) and CF 3 ( 7 ). A V-shaped correlations obtained between the binding energy of the Fe 2p 3/2 photoelectron line and Hammett constants (σ R ) of the R-groups as well as the oxidation potential of the Fe II /Fe III couple, E pa , indicates that there are different modes of zwitterion formation, of electron-donating and electron-withdrawing R-substituents, after photoemission of an electron during the XPS measurements. The intensity of the satellite peak ( I ratio ) within the substructure of the photoelectron line is an indication of the amount of charge being transfer from the donor (ferrocenyl-fragment) to the acceptor fragments. The link between the Gordy group electronegativities, λ R , and I ratio show that more charge is being transfer from Fc in chalcone with more electron withdrawing R-groups. During electron transfer processes (like electrochemical oxidation or photoemission) the chalcone undergoes inner-sphere reorganisation to compensate for the positively charged species which is formed. The I ratio is also an indication of the degree of inner-sphere reorganisation, while the carbonyl stretching frequency ( v CO as measured by ATR FTIR) is a measure of the amount of energy of required for this inner-sphere reorganisation. The link between I ratio and v CO showed that as the degree of inner-sphere reorganisation increases, more energy is required for this inner-sphere reorganisation. [ABSTRACT FROM AUTHOR]

A series of ferrocenyl-functionalized β-diketonato manganese(III) complexes, [Mn(FcCOCHCOR)3] with R = CF3, CH3, Ph (phenyl) and Fc (ferrocenyl) was subjected to a systematic XPS study of the Mn 2p3/2 and Fe 2p3/2 core-level photoelectron lines and their satellite structures. A charge-transfer process from the β-diketonato ligand to the Mn(III) metal center is responsible for the prominent shake-up satellite peaks of the Mn 2p photoelectron lines and the shake-down satellite peaks of the Fe 2p photoelectron lines. Multiplet splitting simulations of the photoelectron lines of the Mn(III) center of [Mn(FcCOCHCOR)3] resemble the calculated Mn 2p3/2 envelope of Mn3+ ions well, indicating the Mn(III) centers are in the high spin state. XPS spectra of complexes with unsymmetrical β-diketonato ligands (i.e., R not Fc) were described with two sets of multiplet splitting peaks representing fac and the more stable mer isomers respectively. Stronger electron-donating ligands stabilize fac more than mer isomers. The sum of group electronegativities, ΣχR, of the β-diketonato pendant side groups influences the binding energies of the multiplet splitting and charge transfer peaks in both Mn and Fe 2p3/2 photoelectron lines, the ratio of satellite to main peak intensities, and the degree of covalence of the Mn-O bond. [ABSTRACT FROM AUTHOR]

A new synthetic route involving ligand exchange towards a series of ruthenocenyl-containing β-diketonato titanocene complexes of the type [Ti IV (C 5 H 5 ) 2 (RcCOCHCOR)][ClO 4 ] with Rc = Ru II (C 5 H 5 )(C 5 H 4 ) and R = C 10 F 21 ( 1 ), CF 3 ( 2 ), C 6 F 5 ( 3 ), C 10 H 21 ( 4 ), CH 3 ( 5 ), Rc ( 6 ) and Fc = Fe II (C 5 H 5 )(C 5 H 4 ) ( 7 ) are described. The complex [Ti IV (C 5 H 5 ) 2 (RcCOCHCOCH 3 )][ClO 4 ], 5 , (Z = 4) crystallised in the monoclinic space group P2 1 /n. A cyclic voltammetric electrochemical study in CH 2 Cl 2 /0.1 M [NBu 4 ][B(C 6 F 5 ) 4 ] showed the one-electron transfer redox processes of the Ti III /Ti IV and Rc/Rc + couples exhibited irreversible electrochemical behaviour. In CH 3 CN/0.1 M [N( n Bu) 4 ][PF 6 ], the ruthenocenyl couple switched to an electrochemically and chemically irreversible two-electron transfer redox couple, Rc/Rc 2+ , involving the Ru IV redox centre. The redox potentials of the Ti III /Ti IV , Rc/Rc + and Rc/Rc 2+ couples were in the range −642 < E o′ < −1479 mV (both solvents), 1016 mV < E o′ < 1034 mV (CH 2 Cl 2 ) and 609 mV < E o′ < 832 mV (CH 3 CN) vs . the free ferrocene couple, FcH/FcH + , respectively. The Fc/Fc + redox process associated with 7 was observed at E o′ = 0.259 (CH 3 CN) and 0.235 V (CH 2 Cl 2 ). The cytotoxicity of [Ti IV (C 5 H 5 ) 2 (RcCOCHCOCF 3 )][ClO 4 ], 2 , against CoLo DM320 and HeLa cells, IC 50 = 10.2 and 9.7 μmol dm −3 respectively, was found to be in the same order of magnitude as those of the free ligand, RcCOCH 2 COCF 3 . [ABSTRACT FROM AUTHOR]

Reaction of [Mn3(OAc)6O•3H2O]+ (1) with ferrocenyl β-diketones of the type FcCOCH2COR with R = CF3 (2a) and CH3 (2b), Ph = C6H5 (2c), and Fc = FeII(η5-C5H4)(η5-C5H5) (2d) yielded a series of ferrocene-functionalized β-diketonato manganese(III) complexes 3a-3d, respectively, of general formula [Mn(FcCOCHCOR)3]. The mixed-ligand β-diketonato complex [Mn(FcCOCHCOFc)2(FcCOCHCOCH3)] (4) was obtained by reacting mixtures of diketones 2b and 2d with 1. A single-crystal X-ray structure determination of 3b (Z = 2, triclinic, space group P1̅) highlighted a weak axial elongating Jahn-Teller effect and a high degree of bond conjugation. An X-ray photoelectron spectroscopic study, by virtue of linear relationships between group electronegativities of ligand R groups, χR, or ∑χR, and binding energies of both the Fe 2p3/2 and Mn 2p3/2 photoelectron lines, confirmed communication between molecular fragments of 2a-2d as well as 3a-3d. This unprecedented observation allows prediction of binding energies from known β-diketonato side group χR values. [ABSTRACT FROM AUTHOR]

Abstract: Chalcones of the type Mc-CO–CH-CO–CH Mc-CO–CHh Mc=Fc=ferrocenyl or Rc=ruthenocenyl, and Ph=phenyl were synthesized. Synthesis was achieved by base catalyzed Claisen–Schmidt condensation of the appropriated acetyl and aldehyde in ethanol. Cyclic voltammetry in CH3CN in the presence of 0.1moldm−3 [N(Bu)4][PF6] revealed chemical and electrochemical reversible behaviour for the Fc/Fc+ couple and irreversible electrochemistry for the two electron Rc/Rc2+ couple. The potential ranges for the Fc/Fc+ couple varied in the range 138⩽ E°′⩽302mV while E pa for Rc/Rc2+ couple was between 358 and 510mV vs. FcH/FcH+, the internal standard. Chalcones with the carbonyl group adjacent to the metallocene, are more difficult to oxidize. [Copyright &y& Elsevier]

The general synthetic strategy towards water-soluble biodegradable drug carriers and the properties that they must have are discussed. The syntheses of water-soluble biodegradable copolymers of lysine and aspartic acid as potential drug-delivering devices, having amine-functionalised side chains are then described. Covalent anchoring of carboxylic acid derivatives of the antineoplastic ferrocene and photodynamically active phthalocyanine moieties to the amine-containing drug carrier copolymers under mild coupling conditions has been achieved utilising the coupling reagent O-benzotriazolyl-N,N,N′,N′-tetramethyluronium hexafluorophosphate to promote formation of the biodegradable amide bond. Even though the parent antineoplastic ferrocene and phthalocyanine derivatives are themselves insoluble in water at pH < 7, the new carrier-drug conjugates that were obtained are well water-soluble. [ABSTRACT FROM AUTHOR]

[Display omitted] Three different classes of ferrocenyl-containing β-keto compounds Fc-CO-CH 2 -CO-R were synthesised to obtain two β-diketones with R = CH 3, 3 , and R = Fc (ferrocenyl = FeII(C 5 H 5)(C 5 H 4)), 4 , a β-ketoester, 5 , with R = OEt and a β-ketoamide, 6 , with R = NH 2. The β-diketones exhibited keto ⇌ enol tautomerization with the enol form Fc-CO-CH=C(OH)-R as the dominant isomer. Both the β-ketoester and β-ketoamide primarily existed in the keto form. FTIR and 1H NMR measurements could distinguish between keto and enol isomers. Dilute CHCl 3 solutions of 3 and 4 exhibited FTIR ѵ C=O keto vibrations between 1627 and 1712 cm−1 and ѵ C=O enol vibrations between 1590 and 1660 cm−1. X-ray photoelectron spectroscopic (XPS) measurements showed keto isomer Fe 2p 3/2 photoelectron lines at smaller binding energies than enol isomers. Significantly lower calculated molecular energies of the keto form of the β-ketoester 5 and β-ketoamide 6 utilising the Gaussian09 suite of programs at the B3LYP (uB3LYP for open-shell species), confirmed that 5 and 6 almost exclusively exists in the keto conformation. Cyclic voltammetry also distinguished between keto and enol isomers, and it was found that the electrochemical reversible ferrocenyl formal oxidation potential, E °ꞌ, of keto isomers of compounds can be estimated with the equation E °ꞌ keto = 170.99χ R –57.57 where χ R is the group electronegativities of R in FcCOCH 2 COR. This result complements earlier research that enables calculation of the ferrocenyl formal oxidation potentials of enol isomers of β-diketones. Computational studies further showed that the HOMO orbitals of 3 – 6 is exclusively on the Fe centre and computed Mulliken spin densities on the d xy orbital of the oxidised iron species approached 1 e−. [ABSTRACT FROM AUTHOR]

Abstract: A comparative investigation of seven ferrocene-containing chalcones (Fc–CO–CH;C6H4R, with R=OCH3, CH3, Ph, t Bu, H, Br and CF3) has been performed based on their electrochemical and spectroscopical behavior as well as with DFT calculations. These compounds were prepared by Claisen-Schmidt condensation of acetylferrocene and the appropriate benzaldehyde derivative. All compounds exhibited reversible chemical and electrochemical behavior, as confirmed by ΔE =83−93mV and i pc/i pa =0.93−1.00. The formal reduction potential E°′ for the compounds ranged between 231.0 and 261.5mV versus FcH/FcH+ as an internal standard. The UV–Vis spectra of all ferrocene-containing chalcones showed the characteristic peaks for aromatic systems at ±380nm and a peak in the visible region at ±490nm, which is attributed to the ferrocene moiety. FTIR of all the ferrocene-containing chalcones showed a characteristic CO stretching peak at ±1650cm−1. DFT calculated HOMO energies and ionization potentials correlate well with experimentally measured E°′ values. [Copyright &y& Elsevier]

Abstract: Enhanced electrochemical resolution of anodic processes is possible in the presence of [N( n Bu)4][B(C6F5)4], 1, as supporting electrolyte over that obtained in the presence of [N( n Bu)4][PF6]. By changing the anion of the supporting electrolyte to a salt having [B(C6F5)4]−, anions, electrochemical processes of especially cationic analytes can benefit. Thus, the redox chemistry of 0.5mmoldm−3 solutions of [Ru2(μ-FcCOO)4·(CH3CH2OH)2][PF6], 2, Fc=ferrocenyl, in CH2Cl2/[N( n Bu)4][B(C6F5)4] were found to involve four well-resolved ferrocenyl-based electrochemical reversible redox processes as well as reduction of RuIII–RuII. At 1.0mmoldm−3 concentrations of 2, or in the presence of [N( n Bu)4][PF6], the four ferrocenyl processes coalesced into only two waves as a result of (Fc+)⋯() ion paring. Seventeen of the possible 18 one-electron transfer processes of the biscadmium trisphthalocyaninato complex [Cd2{Pc(C6H13)8}3], 3, could be observed in THF/[N( n Bu)4][B(C6F5)4], but the electrochemical window of CH2Cl2/[N( n Bu)4][B(C6F5)4] only allowed detection of 15 of these processes. Although reduction processes were unaffected, THF solvation leading to species such as (3 n +)(THF) x with 1⩽ n ⩽4 and x ⩾1 as well as ion pair formation of the type (3 n +)⋯() prevented good resolution of oxidation processes. The CH2Cl2/[N( n Bu)4][B(C6F5)4] system also allowed detection of reversible one-electron transfer ferrocenyl (Fc/Fc+) and ruthenocenyl-based (Rc/Rc+) processes for both enol and keto isomers of the β-diketone FcCOCH2CORc, 4, Rc=ruthenocenyl. In CH3CN/[N( n Bu)4][PF6], the ruthenocenyl moiety was oxidised to a RuIV species. [Copyright &y& Elsevier]

Surface-hydroxylated silicon wafers, 8, were reacted with 3-aminopropyltrimethoxysilane, 9, to create wafers with amine-functionalized surfaces, 10. The metallocenylaldehydes FcCHO, 1 (Fc = ferrocenyl = FeII(C5H5)(C5H4)), RcCHO, 2 (Rc = ruthenocenyl = RuII(C5H5)(C5H4)), and OcCHO, 3 (Oc = osmocenyl = OsII(C5H5)(C5H4)) as well as the carboxylic acids FcCOOH, 4, RcCOOH, 5, OcCOOH, 6, and Cc+COOH·PF6 −, 7 (Cc+ = cationic cobaltocenium = [CoIII(C5H5)(C5H4)]+), were reacted with 10 to covalently anchor the metallocenes on the wafers either via an imine (–CH N–) or amide (–NHCO–) bond. The aldehydes were anchored more effectively than the carboxylic acids. Binding energies of all important atoms in all seven systems were determined by XPS measurements. Metal binding energies of the amide-bonded metallocenes were consistently larger (up to 0.6 eV) than those of the imine-anchored systems. AFM and SEM measurements showed that the covalently anchored metallocenes aggregate into nano-islets of diameter between 40 and 100 nm depending on the metallocene and type of anchoring bond. Up to seven additional layers of unreacted metallocenylaldehyde or -acid further stacked on top of the main layer of metallocene to form each islet. These additional layers of metallocene of each islet are stabilized by a large network of secondary and/or tertiary bonding forces. The main film surfaces have average thicknesses ranging between 2 and 6 nm, while film roughness, which is mostly associated with the islets, was with one exception (that of the Oc–CONH– surface 14) between 17% and 68% of the film thickness. The crystal structures for OcCHO, 3, and Cc+COOH·PF6 −, 7, was determined and the observed tertiary and secondary intermolecular interactions between independent molecules explains the formation of the nano-islets of each metallocene when anchored onto the aminated silicon wafers. [ABSTRACT FROM AUTHOR]